The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 15, 2002
Filed:
Sep. 27, 2000
Matsushita Electric Works, Ltd., Kadoma, JP;
Abstract
An improved light responsive semiconductor switch with shorted load protection capable of successfully interrupting a load overcurrent. The switch is includes an output transistor which is triggered by a photovoltaic element to connect a load to a power source thereof, and an overcurrent sensor which provides an overcurrent signal upon seeing an overcurrent condition in the load. A shunt transistor is connected in series with a current limiting resistive element across the photovoltaic element to define a shunt path of flowing the current from the photovoltaic element through the current limiting resistive element away from the output transistor. A latch circuit is included to be energized by the photovoltaic element and to provide an interruption signal once the overcurrent signal is received and hold the interruption signal. The interruption signal turns on the shunt transistor so as to flow the current from the photovoltaic element through the shunt path, thereby turning off the output transistor for interruption of the overcurrent. The current limiting resistive element is connected in series with the shunt transistor to limit the current from the photovoltaic element when the shunt transistor is turned on, thereby providing a supply voltage from the photovoltaic element to the latch circuit. Thus, the latch circuit is enabled to keep providing the interruption signal for reliable interruption of the overcurrent.